Category: 50 Observational gait scale

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Mar 15 2015

Observational Gait Scale

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I. Descriptive Information:

Title: Observational Gait Scale (OGS)

Edition: The OGS is a modified version of the Physician’s Rating Scale (Koman et al., 1994). The Physician’s Rating Scale (PRS) was created to examine the gait of young children with cerebral palsy in the sagittal plane after intramuscular injections of botulinum toxin type-A (BTX-A) for equinus gait. This scale did not appear to be sensitive or reliable in detecting specific changes after treatment with BTX-A (Corry et al., 1998). To improve the sensitivity of this scale, alterations were made and it was turned into the OGS (Boyd and Graham, 1999). Alterations to the PRS included the removal of three of the original sections (Equinus foot, Hind foot, Speed of gait) along with adding a section on “Change” (which aimed to improve discrimination between the two treatment groups in the Corey et al. study).

Dates of Publication and Revision: Published in 1999

Author (s): Roslyn N. Boyd and H. Kerr Graham created the OGS in 1999 (Mackey et al. examined reliability/validity of OGS in 2003).

Source (publisher or distributor, address): Source of test could not be found. The address of where the study by Boyd and Graham was conducted: (Hugh Williamson Gait Laboratory, Royal Children’s Hospital, Flemington Road, Parkville, Melbourne, Victoria 3052, Australia). A copy of the OGS form can be found here:

Costs (booklets, form, kit): Cost of OGS form is not listed online. Form can be viewed from the above source. The only major costs would potentially be if video analysis equipment for video recording or software was utilized for OGS scoring like in the Boyd and Graham, Mackey et al., and Pool et al. studies. In the powerpoint presentation by Julie Bouck, analyzing gait via video software is not mentioned so this could potentially be completed in the clinic in the presence of the patient.

Purpose: The main purpose of the OGS is to rate gait parameters from video recordings utilizing a structured scale. The OGS seeks to evaluate or measure the amount of change in an individuals gait pattern over time. The OGS was created as a simple low-technology tool to aid in the biomechanical assessment in the clinical setting specifically the knee joint during mid-stance (crouch and recurvatum). Boyd et al., cite that this test may be useful when children are too small or are insufficiently cooperative for instrumented gait analysis. Furthermore, they had found this scale to be very useful when analyzing a typical walk viewed on split-screen video in slow motion.

Type of Test (eg, screening, evaluative; interview, observation, checklist or inventory): The OGS is an evaluative/observational test that incorporates qualitative notions of gait. When analyzing gait, the examiner has to check the correct boxes in each section of the OGS.

Target Population and Ages: Target age range is from 6-21 in children and young adults with cerebral palsy. The National Guideline Clearinghouse recommends the OGS for those that demonstrate idiopathic toe walking through gait assessment.

Time Requirements – Administration and Scoring: None of the sources referenced at the bottom cite the exact length of time to complete the OGS. Mackey et al. cite that “This version of the PRS has more complexity and is more time consuming.” No specific time frames were given online.


 II. Test Administration

Administration: Child either ambulates in front of camera or clinician while demonstrating most typical/natural gait pattern. An experienced clinician then scores the OGS while analyzing the gait pattern from both frontal and lateral views by checking off the correct boxes that correspond with the demonstrated gait deviation in each section of the OGS form. If the patient is videotaped then the clinician will watch video recordings to score the OGS. Again, the most critical notion to this test is to make sure the child is ambulating with their most typical gait pattern.

Scoring: The OGS is a scale with 8 sections (1: Knee position in midstance, 2: Initial foot contact, 3: Foot contact at midstance, 4: Timing of heel rise, 5: Hindfoot at midstance, 6: Base of support, 7: Gait assistive devices, and 8: Change) where you score both the left and right lower extremities by selecting the appropriate numerical value. Specifically, the knee position in midstance section has two subsections where you have to select the appropriate numerical value in either the Crouch or Recurvatum subsections (Neutral is under crouch). A perfect score would be a 22 on each limb. Even though this was not specifically stated, it seems that the higher the score, the less impairments demonstrated by the child.

Type of information, resulting from testing (e.g. standard scores, percentile ranks): The OGS gives a standard score out of 22. The eight sections of the OGS portray specific information pertaining to gait including: knee position at midstance as either a crouch or recurvatum; initial contact of the foot with either being on the forefoot, foot-flat, or heel; foot contact description at midstance; the amount and timing of heel rise; description of hindfoot at midstance as either varus, valgus, or neutral; the amount of base of support; assistive devices utilized; and change with either being worse, better, or neutral. Overall, several items in this test are geared to quantify visually the relationship between the ankle and knee position during stance. With utilizing the OGS, Boyd et al. looked to distinguish true equinus (plantarflexion/knee extension coupled in midstance) from apparent equinus (hamstring spasticity is greater than calf spasticity).

Environment for Testing: Clinic setting or gait analysis laboratory for adequate video recordings. As mentioned above, Boyd et al. and Mackey et al. analyzed gait of individuals with cerebral palsy via video recordings. In the powerpoint by Julie Bouck on Pediatric Gait Assessment, she does not specify whether the OGS has to be completed by analyzing video recordings or examining a patient in the clinic.

Equipment and Materials Needed: Adequate amount of space to allow the patient to ambulate on a flat floor surface. Potentially a camera for videotaping and lab for child to ambulate in while videotaping.

Examiner Qualifications: Experienced clinicians are required to complete this test. Mackey et al. utilized a pediatric PT and an orthopedic pediatric surgeon to examine intra-rater and inter-rater reliability and validity of the OGS. Both observers worked in a tertiary-level pediatric hospital and had 5 years experience with observing gait and reviewing gait analyses in children with cerebral palsy. Also, both of these observers had up to 2 years experience utilizing the OGS in the clinical setting.

Psychometric Characteristics: This test has been found to be valid and reliable. MCIDs and responsiveness to change values have not been established for this test at this time.

Standardization/normative data: Normative values have not been established for this test at this time.

Evidence of Reliability: In Rathinam et al., the OGS was reported to have very good inter-rater reliability, however only the sagittal plane (ankle/foot and knee joints) items scored maximum agreement. Mackey et al. found the OGS had acceptable inter-rater and intra-rater reliability for knee and foot position in midstance, initial foot contact, and heel rise. There were also lower intra-rater reliabilities found for section 5 (hindfoot position) and section 6 (base of support). Overall, data from this study suggests that the first four sections of the OGS scale have an acceptable level of reliability and validity when assessing gait in children with spastic diplegia and problems principally in the sagittal plane.

Evidence of Validity: Mackey et al cited that, “Correlation of 3-dimensional gait analysis data with OGS scores for the first four sections showed high validity for our most reliable observer.” This comparison with 3-dimensional gait analysis suggests that the sections of knee and foot position in mid-stance, initial foot contact, and heel rise have high validity.

Discriminative: This test does not have the discriminative ability to differentiate between young or older aged children with cerebral palsy. The only discriminative quality in the current research is that it can help distinguish between a true equinus and apparent equinus.

Predictive: This test is not a predictive measure in that it does not have the ability to predict changes in motor function related to gait with age progression in children with cerebral palsy.


III. Summary Comments

Strengths: The OGS has high reliability and validity. It includes specific measuring properties that are geared toward the impairments of children with cerebral palsy. It requires no written qualitative gait analysis therefore increasing efficiency on part of the clinician. It looks at change over time in both lower extremities.

Weaknesses: The OGS is somewhat complex with requiring a good amount of experience whether it be to set the video recording up with the specific markers on the joints of interest (if computer software or video recordings are utilized) as well as to make accurate assessments. There are also no normative, MCID, or responsiveness to change values and it doesn’t have any predictive qualities. It has only been validated for children with cerebral palsy. Pool et al. cite that the OGS has poor sensitivity. This test is also not listed on limiting its accessibility to the public. Mackey et al., cite that “it takes a long time to complete this test and videos of young children are often more difficult to record and standardize due to younger children’s lack of compliance.”

Clinical Applications: A PT with enough experience in pediatrics can perform this in the clinic and have reasonable validity to look for change over time. This test could also help guide the examination for a novice PT in pediatrics in terms of making sure to document on specific aspects of gait for patients with cerebral palsy like knee position at midstance.


IV. Summary of research article utilizing OGS:

Pool D, Blackmore AM, Bear N, et al. Effects of short-term daily community walk aide use on children with unilateral spastic cerebral palsy. Pediatr Phys Ther. 2014 Fall;26(3):308-17. doi: 10.1097/PEP.0000000000000057.

The main purpose of this article was to look at how the Walk Aide, a form of functional electrical stimulation (FES), effects impairments affecting gait in children with unilateral spastic cerebral palsy. The authors hypothesized that 8 weeks of FES would improve ankle dorsiflexion strength, ROM, selective motor control, gastrocnemius spasticity, balance, and gait in this patient population. The intervention protocol included a 20-week, multiple single-subject A-B-A design with a 6-week pre-FES phase, an 8-week FES phase, and a 6-week post-FES phase (children wore their AFOs during the pre-FES phase but not during FES and post-FES phases). Twelve children from the ages of 5 to 16 wore the Walk Aide diurnally for 8 weeks. During the FES phase, children were asked to use the device for at least 1 hour a day for 6 days a week. Measurements were taken on a weekly basis for ankle range of motion, dorsiflexion and plantar flexion strength, selective motor control, gastrocnemius spasticity, single-limb balance, Observational Gait Scale (OGS) score, and self-reported toe drag and falls. When comparing the pre-FES phase to the FES phase, significant improvements were seen for ankle range of motion, selective motor control and strength, along with reductions in toe drag, spasticity, and falls (these improvements were maintained during the post-FES phase). However, no change was noticed for OGS score. The main conclusion was that this study supports the intermittent short-term use of FES to address the main impairments affecting gait in children with unilateral spastic cerebral palsy. This is particularly true for children functioning at GMFCS level I.

How OGS was utilized in this study: Silicon Coach Pro7 was the software program used for video analysis. Each child was video-recorded while walking barefoot at a self-selected speed without the Walk Aide. Videos of walking without the Walk Aide were presented in randomized order to a blinded assessor, who gave each child an OGS score out of 20. The section of “change” in the overall gait pattern was omitted to preserve blinding.

Interpretation of OGS results: “The reductions in toe drag and falls were not reflected in the OGS measures, possibly because of poor OGS sensitivity and the lack of quantitative measurements during gait. Given that a change of the ankle joint of as little as 2° can significantly alter foot clearance, the OGS would not have been able to account for such a small difference and may have underestimated the direct effect of FES on foot clearance for the reduction in toe drag and falls.”



Bouck, J. Pediatric Gait Assessment. [Powerpoint]. UPTA Fall Conference; 2014.


Boyd R, Graham HK. (1999) Objective measurement of clinical findings in the use of botulinum toxin type A for the management of children with cerebral palsy. Eur J Neurol 6 (Supp. 14): S23–35.


Corry I, Cosgrove AP, Duffy C, et al. Botulinum toxin A compared with stretching casts in the treatment of spastic equinus: a randomised prospective trial. J Pediatr Orthop. 1998; 18: 304–11.


Koman LA, Mooney J, Smith B, et al. Management of spasticity in cerebral palsy with botulinum-A toxin:report of a preliminary, randomised, double-blind trial. 1994; J Pediatr Orthop. 14: 299–303.


Mackey AH, Lobb GL, Walt SE, et al. Reliability and validity of the Observational Gait Scale in children with spastic diplegia. Dev Med Child Neurol. 2003 Jan; 45(1):4-11.


Pool D, Blackmore AM, Bear N, et al. Effects of short-term daily community walk aide use on children with unilateral spastic cerebral palsy. Pediatr Phys Ther. 2014 Fall;26(3):308-17. doi: 10.1097/PEP.0000000000000057.


Rathinam, C.;Bateman, A,; Peirson,; Skinner, J;: Observational gait assessment tools in paediatrics –A systematic review. Journal of Gait and posture 40,279-285, 2014.

Mar 03 2017

Observational Gait Scale – Update (3/2/2017)

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(I reviewed the original OGS post and the data is still up to date)

Dursun N, Gokbel T, Akarsu M, Dursun E. A Randomized Controlled Trial on Effectiveness of Intermittent Serial Casting on Spastic Equinus Foot in Children with Cerebral Palsy After Botulinum Toxin-A Treatment. Am J Phys Med Rehabil. 2016;

Purpose: To explore the efficacy of a combined treatment approach of intermittent, progressive serial casting and physical therapy (PT) after botulinum toxin-A (BTX-A) injections on spasticity, passive range of motion (PROM), and gait of children with CP.

Study Population: 54 patients between ages 3 and 17 with diagnosis of CP according to Rosembaum criteria, hemiplegic or diplegic type of involvement, a Gross Motor Functional Classification System level of I, II, or III, presence of unilateral or bilateral spastic equinus foot deformity with shortened plantar flexors, a Modified Ashworth Scale (MAS) score of 3 in plantar flexor muscles, and a scheduled BTX-A injection treatment for spastic plantar flexors.

Methods & Interventions: Patients were randomly assigned to either a casting group or control group (in a ratio of 2:1).  BTX-A injections were administered to target muscle groups of all patients under guidance of electrical stimulation and in an individualized manner.  All patients received injections to plantar flexors, but several patients from both groups received  multilevel injections.  Both groups participated in a PT program with 1-hour sessions, 5 days per week, for 3 weeks.  The PT program focused on stretching, strengthening, weight bearing, balance, proprioception, and ambulation activities and exercises.  The casting group received a series of progressive casting on top of the PT.  Ankle joint positioning was progressed based on improvements made in passive dorsiflexion.  All patients were followed for 12 weeks and data was collected along the way regarding any changes in muscle tone and spasticity, PROM, gait function, or if there was an adverse event.  Primary outcome measures included PROM and MAS, and secondary outcome measures included the Tardieu, Observational Gait Scale (OGS), and Physician Global Assessment (PGA).  Comparison of baseline, week 4, and week 12 within-group evaluations of PROM, spasticity measurements, OGS, and PGA were performed using Friedman test.  The Mann-Whitney U test was applied and used for all comparisons between independent group medians.

Outcome Measures:  Muscle tone and spasticity were assessed and measured using the MAS and Tardieu scales.  All patients were videotaped to evaluate gait during each visit per the OGS protocol.  A physician blinded to the treatment protocol performed the MAS, Tardieu, and OGS assessments for all patients.

Results: There were 3 drop-outs along the way, bringing the total number of participants down to 51.  There were no statistically significant differences found between the casting and control groups regarding type of involvement, Gross Motor Functional Classification System levels, age, and sex (P > 0.05 for all parameters).   There were no statistically significant differences found between the casting and control groups related to baseline spasticity data (P > 0.05 for all parameters).  Both groups showed statistically significant improvements in angle of catch at fast speed and spasticity angle (both components of Tardieu Scale), MAS and PROM (P < 0.001 for all parameters of both groups).  A statistically significant decrease in spasticity grade (component of Tardieu Scale) was also found in the casting group (P < 0.001).  Statistically significant improvements for all parameters (P < 0.05) were determined to have been reached by week 4 and maintained at week 12 using post hoc data analysis.  Between group analysis revealed that average changes in PROM, MAS, angle of catch at fast speed, and spasticity angle measures were significantly higher in the casting group compared to the control group.  There were statistically significant improvements in OGS scores for both groups.

Strengths/Limitations: The interventions used seemed to be strong components of the study as both groups showed improvements in almost all outcome measures.  That being said, there was little information regarding what specific PT interventions were used and whether PT varied based on age or not.  The study also had a fairly wide age range, which could have potential implications regarding the applicability of the data to a particular age group.  On the flip side, having a wide age range could be considered a strength in terms of the generalizability of the data.

Conclusion: The study showed that certain populations of children with specific types of CP may indeed benefit from a progressive, intermittent serial casting intervention when combined with PT (after having received BTX-A injections) as shown by statistically significant improvements in various outcome measures related to muscle tone and spasticity, gait function, joint mobility, and PROM in affected spastic muscles.

Mar 07 2018

Observational Gait Scale- Update (3/7/2018)

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I have reviewed the previous posts on OGS, and the information remains up-to-date.

Borel S, Schneider P, Newman CJ. Video analysis software increases the interrater reliability of video gait assessments in children with cerebral palsy. Gait and Posture. 2011; 33: 727-729.

Purpose:  This study sought to determine if video analysis software improves the interrater reliability of visual gait assessment, specifically with the Observational Gait Scale (OGS), in children with cerebral palsy (CP).

Study Population: Twelve children (9 males and 3 females) with CP were video recorded in an outpatient rehabilitation clinic. Age of the children ranged from 5 to 14 years old. Five children were diagnosed with bilateral spastic CP and 7 children with unilateral spastic CP. The children were able to ambulate at a self-selected pace over a linear 10 meter walkway. Videos were recorded during ambulation in both the sagittal and frontal planes.

Methods: Twenty of the gait videos were randomly selected to be viewed during this study. Two video observers with differing levels of clinical experience were selected to assess the video recordings: a final year medical undergraduate and a physiotherapist with more than 10 years of clinical experience working with children with cerebral palsy. Both scorers were familiar with OGS before the study, and both had been provided specific instructions on criteria scoring.  Each video was viewed randomly by both scorers, once with Windows Media Player (WMP) and a second time with the video analysis software Dartfish. WMP allowed observers to use slow motion and image pausing, while Dartfish allowed for more sophisticated slow motion and onscreen measurements. Observers utilized the following Dartfish software functions: digital goniometer for measurements of knee and hindfoot position in midstance; timing measurements for initial contact, midstance, and terminal stance; and line drawing for measurements of base of support. Agreement between scorers was measured for each individual video and for overall OGS score, both with and without video analysis software, using weighted Cohen’s kappas.

Interventions: No intervention was applied to participants as part of this study.

Outcome Measure: The OGS was used to score each video based on the following criteria: 1) knee position in midstance, 2) initial foot contact, 3) foot contact at midstance, 4) timing of heelrise, 5) hindfoot at midstance, and 6) base of support. The following criteria were not assessed during the analysis:  7) gait assistive devices and 8) changes in gait over time.

Results: When using WMP to assess one video, the average time was 10 + 2 minutes. When using the Dartfish software, the average time was 18 + 3 minutes to assess one video. Mean total OGS score when using WMP was 13.8 + 4.6 for scorer 1 and 15.1 + 3.4 for scorer 2. Mean total OGS score when using Dartfish was 13.1 + 4.0 for scorer 1 and 13.6 + 3.3 for scorer 2. Interrater agreement was improved with the use of video analysis software for knee (kappa value 0.344 to 0.591) and hindfoot (kappa value 0.160 to 0.346) position during midstance, foot contact (kappa value 0.700 to 0.854) during midstance, timing of heelrise (kappa value 0.769 to 0.835) during terminal stance, and overall OGS score (kappa value 0.778 to 0.809). Little to no change was seen for initial foot contact (kappa value 0.796 to 0.797) or base of support (kappa value 0.366 to 0.371).

Strengths/Limitations: One strength of this study is that the two observers had knowledge of the OGS, but had differing levels of experience with gait analysis. This detail increases the ability to generalize the results of this study to the broad spectrum of expertise that exists in the field of physical therapy.  Additionally, the videos were viewed in random order and the scorers alternated between using WMP and Dartfish first. This prevents the analysis bias of using one video viewing tool over the other. A limitation of the study is that only two scorers were involved in the analysis. Additional scorers should be included to improve the strength of the study.

Conclusion: While the OGS has previously been validated, this study shows that video analysis software can help improve interrater reliability. The OGS items that require direct angle measurements, such as knee flexion and hindfoot position during midstance, saw the greatest improvement in interrater agreement. Items that require precise timing, such as heelrise, generally saw a moderate improvement in interrater agreement, as scorers were able to analyze timing with precision to 20 ms.  Overall, the use of video analysis software can improve the interrater reliability of the OGS without a significant increase in analysis time.